1. Field of the Invention
This invention relates generally to cherry-picker-type aerial lift support apparatus, and more specifically relates to a table mount-type frame removably associated with a mobile vehicle, said frame adapted to support an extensible aerial lift arm but while reducing tortional fatigue to the vehicle frame over time.
2. Prior Art
The widespread use of aerial support lifts on mobile carriers has given rise to a variety of configurations so as to satisfy a particular need. As the safety of a human operator is placed in peril by being raised to relatively great heights in the cherry-picker bucket attached to the extensible aerial lift boom which in turn is connected to the carrier vehicle, the configuration of the boom, turret and support frame must be designed to allow a minimum of deflection of the vehicle subframe or chassis from movement of the boom and turret. The most common remedy for suppressing undesired structural deflections is to use extendible feet means such as shown in elements 66 and 67 of U.S. Pat. No. 4,700,851 to Reeve et al. Such feet means, however, add to the cost of a lifting apparatus, therefore leaving an alternate embodiment preferred.
It is also necessary in the course of operating such aerial lifts to either repair the lift apparatus itself or the carrier vehicle without disabling the carrier vehicle or aerial lift apparatus, respectively. For other reasons, removable aerial lift assemblies have been proposed, particularly in U.S. Pat. No. 4,407,419, which discloses a portable boom support but which relies on lateral extensible outriggers for lateral stability. Also, U.S. Pat. No. 4,700,851 discloses a portable lift and frame assembly which also relies on extensible feet as referred to supra. In addition, U.S. Pat. No. 3,888,368 discloses an adjustable wrecker attachment having a base frame the proportions of which can be adjusted.
In structures of the type herein described, it has been customary to refer to mounting structures as being either of the bridge-mount type or the table-mount. The bridge-mount type frame has a relatively narrow stance and would be applicable for low loading force conditions. On the other hand, the table-mount type frame has a wider stance both laterally and longitudinally, and is used under higher loading conditions so as to provide higher structural resistance to said loading.